Semiconductor wafer, implantation apparatus for implanting protons and method for forming a semiconductor device

ABSTRACT

A method for forming a semiconductor device includes determining at least one electrical parameter for each semiconductor device of a plurality of semiconductor devices to be formed in a semiconductor wafer. The method further includes implanting doping ions into device areas of the semiconductor wafer used for forming the plurality of semiconductor devices with laterally varying implantation doses based on the at least one electrical parameter of the plurality of semiconductor devices.

TECHNICAL FIELD

Embodiments relate to concepts for semiconductor device structures, andin particular to a semiconductor wafer, an implantation apparatus forimplanting protons and a method for forming a semiconductor device.

BACKGROUND

It may be challenging to achieve doping accuracy in semiconductortechnology. Doping inaccuracies or instability in doping regions maylead to deviations in electrical performance between semiconductor diesfrom different semiconductor wafers, and even between semiconductor diesfrom the same semiconductor wafer. For example, deviations or variationsin the electrical characteristics (e.g. blocking capability) ofsemiconductor devices may exist between semiconductor devices on thesame semiconductor wafer, for example.

SUMMARY

It is a demand to provide concepts for providing semiconductor deviceswith increased reliability.

Some embodiments relate to a method for forming a semiconductor device.The method comprises determining at least one electrical parameter foreach semiconductor device of a plurality of semiconductor devices to beformed in a semiconductor wafer. The method further comprises implantingdoping ions into device areas of the semiconductor wafer used forforming the plurality of semiconductor devices with laterally varyingimplantation doses based on the at least one electrical parameter of theplurality of semiconductor devices.

Some embodiments relate to a semiconductor wafer. The semiconductorwafer comprises a plurality of compensation devices. Each compensationdevice comprises a plurality of device drift regions having a firstconductivity type and a plurality of compensation regions having asecond conductivity type arranged alternatingly in a lateral direction.A breakdown voltage of more than 70% of the plurality of compensationdevices varies by less than 10% from a nominal breakdown voltage of theplurality compensation devices.

Some embodiments relate to an implantation apparatus for implantingprotons. The apparatus comprises a proton implantation module configuredto implant protons into a semiconductor substrate. The apparatus furthercomprises a control module configured to control the implantationsmodule to vary an implantation dose of protons laterally, so thatprotons are implanted with different implantation doses at differentlateral portions of the semiconductor substrate.

Those skilled in the art will recognize additional features andadvantages upon reading the following detailed description, and uponviewing the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

Some embodiments of apparatuses and/or methods will be described in thefollowing by way of example only, and with reference to the accompanyingfigures, in which

FIG. 1A shows a flow chart of a method for forming a semiconductordevice;

FIG. 1B shows a schematic illustration of a multi-chip layout of anelectrical parameter of a plurality of semiconductor devices in asemiconductor wafer;

FIG. 2 shows a schematic illustration of a semiconductor wafer;

FIG. 3A shows a schematic illustration of an implantation apparatus forimplanting protons; and

FIG. 3B shows a further schematic illustration of the implantationapparatus for implanting protons.

DETAILED DESCRIPTION

Various example embodiments will now be described more fully withreference to the accompanying drawings in which some example embodimentsare illustrated. In the figures, the thicknesses of lines, layers and/orregions may be exaggerated for clarity.

Accordingly, while example embodiments are capable of variousmodifications and alternative forms, embodiments thereof are shown byway of example in the figures and will herein be described in detail. Itshould be understood, however, that there is no intent to limit exampleembodiments to the particular forms disclosed, but on the contrary,example embodiments are to cover all modifications, equivalents, andalternatives falling within the scope of the disclosure. Like numbersrefer to like or similar elements throughout the description of thefigures.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. Other words used to describe therelationship between elements should be interpreted in a like fashion(e.g., “between” versus “directly between,” “adjacent” versus “directlyadjacent,” etc.).

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a,” “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises,” “comprising,” “includes” and/or “including,” when usedherein, specify the presence of stated features, integers, steps,operations, elements and/or components, but do not preclude the presenceor addition of one or more other features, integers, steps, operations,elements, components and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which example embodiments belong. Itwill be further understood that terms, e.g., those defined in commonlyused dictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art.However, should the present disclosure give a specific meaning to a termdeviating from a meaning commonly understood by one of ordinary skill,this meaning is to be taken into account in the specific context thisdefinition is given herein.

FIG. 1A shows a flow chart of a method 100 for forming a semiconductordevice according to an embodiment.

The method 100 comprises determining 110 at least one electricalparameter for each semiconductor device of a plurality of semiconductordevices to be formed in a semiconductor wafer.

The method further comprises implanting 120 doping ions into deviceareas of the semiconductor wafer used for forming the plurality ofsemiconductor devices with laterally varying implantation doses based onthe at least one electrical parameter of the plurality of semiconductordevices.

Due to the implanting 120 of doping ions into the device areas of thesemiconductor wafer with laterally varying implantation doses based onthe at least one electrical parameter of the plurality of semiconductordevices to be formed, semiconductor devices which are more reliable maybe provided. For example, a plurality of semiconductor devices to beformed within a semiconductor wafer may be provided with reduceddeviations or inhomogeneity.

The method 100 may include determining 110 the at least one electricalparameter for each semiconductor device (e.g. each semiconductor die) ofa plurality of semiconductor devices (or e.g. a plurality ofsemiconductor dies) to be formed in a semiconductor wafer by measuring avalue of an electric parameter related to each semiconductor device ofthe plurality of semiconductor devices.

The method 100 may include determining 110 the at least one electricalparameter from partially formed or partially completed semiconductordevices, for example. For example, each semiconductor device may includeone or more device doping regions. However, metallization layers orelectrical interconnects may not yet be formed in the semiconductordevices.

The method 100 may include determining 110 the at least one electricalparameter of an electrical device structure formed in each (partiallyformed) semiconductor device of the plurality of semiconductor devices.The electric parameter may be, or may be a value corresponding to (orproportional to) a blocking voltage capability of the electrical devicestructure of a semiconductor device. For example, the electric parametermay correspond to a breakdown voltage Vbd (e.g. a blocking voltagecapability) between a source and a drain of a field effect transistor(FET) device structure of the semiconductor device or between acollector and an emitter of an insulated gate bipolar transistor (IGBT)device structure of the semiconductor device, for example.

The electrical parameter (e.g. the breakdown voltage Vbd) may bemeasured between respective electrodes of the semiconductor device (orthe electrical device structure) or with respect to a test structurearranged within an area of each semiconductor die (or semiconductordevice) and/or within kerf regions of the semiconductor die. The teststructures for monitoring process stability may be arranged in the kerfregions (e.g. the regions between the semiconductor dies which may beused for wafer dicing accomplished by scribing and breaking, bymechanical sawing or by laser cutting), for example. The test structuresmay include p-n junctions between several or any combination of p-dopedregions and n-doped regions, for example. In additional or as analternative, the test structures may also include resistors formonitoring sheet resistance of the p-doped regions and the n-dopedregions. When arranging the test structures in the kerf regions,measurement of the test structures may be carried out before dicing thesemiconductor wafer into singularized semiconductor devices (or dies),for example.

The electric parameter may characterize a charge balance of theelectrical device structure (which may be e.g. a charge compensationdevice structure) of the semiconductor device with respect to a targetvalue (e.g. with respect to a predefined nominal electrical parametervalue). For example, since the charge balance constitutes a referenceparameter for correction of an overall charge in the alternatingly dopedcompensation regions and drift regions (e.g. the n- and p-dopedregions), precision of correction may be improved with respect to acorrection process having the overall charge in the n- and p-dopedregions as the reference parameter for correction. The adjustedimplantation doses (e.g. proton irradiation parameters) may beconfigured to shift a charge balance of the individual chargecompensation device structures in each semiconductor device towards orto a target charge balance of the charge compensation device structurebased on the measured value of the electric parameter.

The value of the at least one electric parameter of the semiconductordevices may be measured by arranging the semiconductor wafer on acarrier and measuring the electric parameter via measurement equipment,for example. The measurement equipment may include a wafer prober, forexample. For example, the semiconductor wafer may be vacuum-mounted on awafer chuck and electrically connected via probes brought intoelectrical contact with the semiconductor wafer. When the electricparameter of a die (or a first semiconductor device) has been measured,the wafer prober moves the semiconductor wafer to the next die (or thenext semiconductor device) and measurement of the electric parameter ofthe next die (or the next semiconductor device) may start, for example.

Optionally, more than one electrical parameter (or e.g. a blockingvoltage or e.g. an electrical resistance) of the plurality ofsemiconductor devices may be determined. The laterally varyingimplantations doses may be determined based on more than one electricalparameter, for example.

FIG. 1B shows an example of a wafer map 150 of a multi-chip layout of atleast one electrical parameter (e.g. a break down voltage) for eachsemiconductor device of a plurality of semiconductor devices to beformed in a semiconductor wafer. The (partially formed or partiallycompleted) semiconductor devices may each be arranged in differentlateral locations with respect to a first lateral direction 151 (X) anda second lateral direction 152 (Y) of the semiconductor wafer. Forexample, the map may include information related to an inhomogeneouslateral distribution of the blocking capability in a compensationscomponent with a nominal (target) breakdown voltage of 500 V. The mapmay include information related to a deviation of the measuredelectrical parameter (e.g. which may have a breakdown voltage range from510 V and 630 V) corresponding to each semiconductor device from thetarget nominal electrical parameter value (e.g. 500V).

Based on the measured electric parameter values of the electrical devicestructures of the plurality of semiconductor devices, implantation doses(or e.g. proton irradiation doses) and/or annealing parameters for eachsemiconductor device (or e.g. for each electrical device structure) maybe chosen or adjusted. For example, at least one of a dose and an energyof proton irradiation may be adjusted based on the measured value of theelectric parameter.

The method 100 may include determining different implantation doses forimplanting the doping ions into a device area of each semiconductordevice of the plurality of semiconductor devices. For example, animplantations dose may be determined for each device area of thesemiconductor device of the plurality of semiconductor devices, so thatthe electrical parameter of each semiconductor device may beindividually adjusted. For example, each semiconductor device may beindividually adjusted such that the electrical parameter is tunedtowards the predefined nominal electrical parameter value (or targetelectrical parameter value). For example, the method 100 may includedetermining a first implantation dose for implanting the doping ionsinto a device area of the first semiconductor device of the plurality ofsemiconductor devices, and determining a second (different) implantationdose for implanting the doping ions into a device area of the secondsemiconductor device of the plurality of semiconductor devices.

The method 100 may include generating an implantation dose mapcomprising the plurality of laterally varying implantation doses to beimplanted into the device areas of the plurality of semiconductordevices based on the measured electrical parameter value beforeimplanting the doping ions into the device areas of the plurality ofsemiconductor devices, for example.

The adjusted implantation doses (e.g. proton irradiation parameters) mayrange between 1*10¹³ ions per cm² and 8*10¹⁴ ions per cm² (or e.g.between 5*10¹³ ions per cm² and 2*10¹⁴ ions per cm², or e.g. between2*10¹⁴ ions per cm² and 8*10¹⁴ ions per cm²), for example. The adjustedimplantation energy may be greater than 30 keV (or e.g. greater than 300keV), or may range between 30 keV and 5.0 MeV (or e.g. 1.0 MeV and 3.0MeV), for example.

The doping ions may be protons, for example. Alternatively oroptionally, the doping ions may include at least one ion type from thefollowing group of ion types, the group of ion types consisting of:hydrogen ions, boron ions, phosphorus ions, aluminum ions, nitrogenions, antimony ions, indium ions, gallium ions or arsenic ions.

Implanting 120 the doping ions into the device areas of the plurality ofsemiconductor devices with laterally varying implantation doses may meanthat device areas of the different semiconductor devices in thesemiconductor wafer are implanted with doping ions at differentimplantation doses. For example, instead of implanting the doping ionsinto the device areas of the plurality of semiconductor devices with ablanket (or uniform) implantations dose over the entire semiconductorwafer, each device area of the semiconductor device of the plurality ofsemiconductor devices may be implanted with doping ions at differentimplantation doses. For example, the doping ions may be implanted into adevice area of the first semiconductor device of the plurality ofsemiconductor devices with a first implantation dose, and into a devicearea of the second (different) semiconductor device of the plurality ofsemiconductor devices with a second different implantation dose.

The method 100 may include implanting 120 the doping ions into a devicearea of at least one semiconductor device of the plurality ofsemiconductor devices to adjust the at least one electrical parameterrelated to the semiconductor device to vary by less than 10% (or e.g. byless than 5%, or e.g. less than 2%, or e.g. less than 1%) from apredefined nominal electrical parameter value. The predefined nominalelectrical parameter value may be a targeted (or desired) value of theelectrical parameter associated with the semiconductor device, forexample. For example, the method 100 may include implanting 120 thedoping ions into device areas of the semiconductor devices of theplurality of semiconductor devices such that the at least one electricalparameter of more than 70% (or e.g. more than 80% or e.g. more than 90%)of the semiconductor devices of the plurality of semiconductor devicesare individually adjusted to vary by less than 10% (or e.g. by less than5%, or e.g. less than 2%, or e.g. less than 1%) from the predefinednominal electrical parameter value.

The doping ions may be implanted into the device areas of thesemiconductor devices with laterally varying implantation doses byvarying a speed of motion, an angle and/or a distance of thesemiconductor wafer with respect to an ion beam implanting the dopingions. For example, irradiation of the semiconductor wafer with adjustedproton irradiation parameters may generate hydrogen-related donorsleading to an increase of n-doping in both the p- and n-doped regions ofthe charge compensation device structure of the plurality ofsemiconductor devices, for example.

A resulting donor concentration and vertical distribution may also beadjusted by an annealing temperature and an annealing duration. Themethod 100 may include further comprising annealing the semiconductorsubstrate after implanting the doping ions into the device areas of theplurality of semiconductor devices with laterally varying implantationdoses. The annealing of the semiconductor substrate may be carried outat a temperature of between 300° C. and 550° C. (or e.g. between 380° C.and 500° C.) for between 0.5 hours and 10 hours (or e.g. between 1 hourand 5 hours), for example.

The doping is effected predominantly in the so-called end-of-rangeregion of the ion (e.g. proton) implantation, and to a lesser extent inthe region radiated through. Annealing of the semiconductor wafer maylead to diffusion of the hydrogen into the irradiated area and may alsoreach the surface radiated through whereby the formation of complexescomprising the hydrogen atoms and the irradiation-induced defects (e.g.vacancies results in the creation of donors, or e.g. so-calledhydrogen-related donors) in this region.

Since at least one of the proton irradiation and annealing parametersare based on the measured value of the electric parameter related to thesemiconductor devices, a precise correction process of charge balance inthe n-doped and p-doped regions of the charge compensation devicestructure may be carried out with respect to an overall depth of avoltage absorbing volume of the charge compensation device structure(e.g. with respect to an overall depth of a drift zone of the chargecompensation device). For example, the hydrogen-related donors mayextend over at least 30% of a vertical extension of a drift zone betweena first side and a second side of the semiconductor substrate. Forexample, a concentration of the hydrogen-related donors may be in arange of 5*10¹³ donor atoms per cm³ and 8*10¹⁴ donor atoms per cm³.

The above-described correction process may be repeated. For example, theelectrical parameter for each semiconductor device of the plurality ofsemiconductor devices may be measured again (or repeatedly as desired).For example, depending on whether the measured electric parameter is outof a range of tolerance, proton irradiation and annealing may be carriedout to increase the number of n-charges in the charge balance of thecharge compensation device structure. For example, depending uponwhether n-type charges or p-type charges dominate the charge balance ofthe charge compensation device structure, the correction process towardsa target charge balance may either dispense with additional protonimplantation and decrease the number of n-type charges in the chargecompensation device structure by an additional annealing process of thesemiconductor substrate or, in a case of excess p-type charges in chargecompensation device structure, the number of n-type charges may beincreased by additional proton implantation and annealing. Alternativelyor optionally, annealing the semiconductor substrate may be carried outwith a thermal budget configured to deactivate at least a part of donorsgenerated by proton irradiation and annealing. Thereby, a concentrationof hydrogen-related donors generated by proton irradiation and annealingmay also be decreased.

By appropriately adjusting parameters such as proton irradiation dose,proton irradiation energy, annealing temperature and annealing duration,the end-of-range area of the doping profile may be adjusted to fallwithin a field stop zone of a charge compensation device, and the areaof almost homogeneous doping with hydrogen-related donors may beadjusted to fall within a voltage absorbing region (e.g. a drift zone ofa charge compensation device structure of a charge compensation device),for example.

The semiconductor wafer may be irradiated with the doping ions (e.g.protons) from a first lateral side, e.g. a front side of thesemiconductor wafer. At the first lateral side, a control electrode(e.g. such as a gate electrode) may be arranged and electrically coupledto a wiring area. Additionally or optionally, the device areas of thesemiconductor wafer may be implanted with the doping ions (e.g. theprotons) from a second lateral side of the semiconductor wafer oppositeto the first lateral side. At the second lateral side, a drain electrodeof a (vertical) FET or a collector electrode of a (vertical) IGBT may bearranged. Alternatively or optionally, the semiconductor wafer may beirradiated with doping ions from the first lateral side and the secondside.

The method 100 may include forming at least part of the electricaldevice structure (e.g. forming device doping regions of the electricaldevice structure) in each semiconductor device of the plurality ofsemiconductor devices before determining 110 the at least one electricalparameter for each semiconductor device of the plurality ofsemiconductor devices and before implanting 120 the doping ions into thedevice areas of the plurality of semiconductor devices with laterallyvarying implantation doses.

The electrical device structure in each semiconductor device may includea compensation device structure, for example. In a compensation devicestructure, the formed device doping regions of the semiconductor devicesmay include a plurality of drift regions having a first conductivitytype (e.g. n-type doped regions) and a plurality of compensation regionshaving a second conductivity type (e.g. p-type doped regions) arrangedalternatingly in a lateral direction, for example. A region comprisingthe first conductivity type may be a p-doped region (e.g. caused byincorporating aluminum ions or boron ions) or an n-doped region (e.g.caused by incorporating nitrogen ions, phosphor ions or arsenic ions).Consequently, the second conductivity type indicates an opposite n-dopedregion or p-doped region. In other words, the first conductivity typemay indicate an p-doping and the second conductivity type may indicate an-doping or vice-versa.

Each semiconductor device (or die) may include the charge compensationdevice structure including the alternating n-doped and p-doped regionsalternating along a lateral direction (e.g. parallel to a main lateralsurface of the semiconductor wafer), for example. The formed n-dopedregions and the p-doped regions may extend in parallel as stripes in adirection orthogonal or perpendicular to the main lateral surface of thesemiconductor wafer, for example. The p-doped regions may includeseparate p-doped pillars or islands surrounded by the n-doped regionbeing a continuous n-doped region, for example. Alternatively ofoptionally, the n-doped regions may be separate n-doped pillars orislands surrounded by the p-doped region being a continuous p-dopedregion. A view of the p-doped islands or n-doped islands (from across-section parallel to the main lateral surface of the semiconductorwafer) may be square-shaped, rectangular, circular or polygonal, forexample.

The device doping regions (e.g. the compensation regions and/or thedrift regions) of the plurality of electrical device structures of theplurality of semiconductor devices in the semiconductor wafer may beformed within a trench and/or by ion implantation before implanting 120the doping ions with laterally varying implantation doses. For example,device doping regions (e.g. the compensation regions and/or the driftregions) may be formed by a multi-epitaxial/multi-implant process or bya trench process, for example.

The formed device doping regions of the semiconductor device (e.g. ofthe compensation device structure) may further include at least one bodyregion, at least one source region, and at least one drain region, forexample. For example, the electrical device structure may include anoptional (n-doped) field stop zone between the charge compensationregions and a (n+-doped) drain region. Additionally or optionally, eachone of the compensation regions (e.g. p-doped regions) may adjoin abottom side of a (p-doped) body region. Alternatively or optionally, the(p-doped) body region may be electrically coupled to a source/emittercontact structure at a first lateral side of the semiconductor wafer viaan optional (p+-doped) body contact region. Additionally or optionally,(n+-doped) source regions may adjoin the first lateral side and may beelectrically coupled to the source contact.

The formed electrical device structure may include a gate structure. Thegate structure may include a gate dielectric and a gate electrodearranged on the semiconductor substrate at the first lateral side, whichmay be configured to control a conductivity in a channel region by fieldeffect, for example. A current flow between the source contact at thefirst lateral side and a drain contact at a second lateral side 128 maybe controlled by the gate structure, for example. The source and draincontacts may include conductive materials such as metal(s) and/or highlydoped semiconductor materials. The source and drain contacts may bepresent before the determining 110 the at least one electrical parameterfor each semiconductor device of the plurality of semiconductor devicesand before implanting 120 the doping ions into the device areas of theplurality of semiconductor devices with laterally varying implantationdoses. Alternatively or optionally, at least one of the source and draincontacts, e.g. the source contact and/or the drain contact may be formedafter determining 110 the at least one electrical parameter for eachsemiconductor device of the plurality of semiconductor devices and afterimplanting 120 the doping ions into the device areas of the plurality ofsemiconductor devices with laterally varying implantation doses. Forexample, the method 100 may include forming the source/drain oremitter/collector contact structure on at least one side of thesemiconductor wafer after implanting the doping ions into the deviceareas of the plurality of semiconductor devices.

Although the method 100 has been described with respect to asemiconductor device including a compensation device structure, it maybe understood that the method 100 may be applied to semiconductordevices with other electrical device structures. For example, eachsemiconductor device may include at least one electrical devicestructure from the following group of electrical device structures. Thegroup of electrical device structures may consist of: a metal oxidesemiconductor field effect transistor device (MOSFET) structure, aninsulated gate bipolar transistor device (IGBT) structure, a chargecompensation transistor device structure, a diode device structure and athyristor device structure. For example, each semiconductor device mayinclude a vertical super-junction (SJ) n-channel field-effect transistor(NFET) device structure, a vertical SJ p-channel FET device structure, alateral SJ FET device structure including source and drain contacts at acommon side, or lateral or vertical insulated gate bipolar transistor(IGBT) device structures, for example.

Each semiconductor device may be a power semiconductor device having abreakdown voltage or blocking voltage of more than more than 10V (e.g. abreakdown voltage of 10 V, 20 V or 50V), more than 100 V (e.g. abreakdown voltage of 200 V, 300 V, 400V or 500V) or more than 500 V(e.g. a breakdown voltage of 600 V, 700 V, 800V or 1000V) or more than1000 V (e.g. a breakdown voltage of 1200 V, 1500 V, 1700V or 2000V), forexample.

The plurality of semiconductor devices (or semiconductor dies) may belocated at different lateral portions of the semiconductor wafer. Forexample, the first semiconductor device and the second semiconductordevice may be located at different lateral portions of the semiconductorwafer. For example, each semiconductor device of the plurality ofsemiconductor devices may be distally separated from each othersemiconductor device by a separation distance in a lateral direction.The lateral direction may be substantially parallel to a lateral surfaceof the semiconductor wafer. For example, a lateral surface or a lateraldimension (e.g. a diameter or a length) of a main surface of thesemiconductor structure may be more than 100 times larger (or more than1000 times or more than 10000 times) than a distance between a firstlateral surface of the semiconductor wafer and a second opposite lateralsurface of semiconductor wafer, for example.

The plurality of semiconductor devices in the semiconductor wafer mayrefer more than one (or e.g. more than ten, or e.g. more than fifty, ore.g. more than hundreds of) semiconductor devices located in thesemiconductor wafer.

Semiconductor devices such as compensation components may require a veryaccurate setting of doping levels (e.g. such as an accurate relationshipbetween p doping regions and n doping regions) in order to obtainsufficient blocking capability. With method 100, doping accuracy may beimproved from typical doping accuracy levels of lower than 1%.Deviations of electrical performance of each device from lot to lotand/or from wafer to wafer may be reduced, and unacceptable lateralvariations in doping and unacceptable spreads in the blocking capabilitymay be reduced. Method 100 may provide an improvement over a feedforward concept, which may be used to improve spreading from lot to lotand/or from wafer to wafer, but which may not allow lateral (doping)inhomogeneity in the wafer to be compensated, for example.

The method 100 may include manufacturing the compensation componentsusing multi epitaxial concepts and/or trench concepts. Based onmeasurements of the compensation components, the lateral distribution ofthe doping values or doping ratios may be determined. Through theimplantation of hydrogen over the whole surface, targeted donors in thedrift zone of compensation components may be created. The incorporateddose may have a lateral variation to homogenize the previous dopingvalues or doping ratios.

The method 100 may include irradiating the highly doped semiconductorwafer (or substrate) or the buffer epitaxial layer with a single, veryhigh implantations energy, for example. Particularly if the annealingtemperature and annealing time are high enough, an end of range peak maylie in the highly doped substrate or in the buffer epi layer. Annealingtemperatures may lie between 450° C. and 500° C. and annealing times maylie between 1 h and 10 h, for example. With such temperature conditions,the implanted hydrogen may be redistributed, so that the donor complexesmay be formed not only at the end-of range of the irradiation, but alsoin the irradiated area, whereby the donor complexes may includevacancies and hydrogen atoms.

The method 100 may include using different (or many) implantationsenergies to obtain a suitable depth distribution of donors. For example,(lower) annealing temperatures (e.g. between 380° C. and 470° C.), and(lower) annealing times (e.g. between 30 min and 5 hours) may be used.Particularly, the variation of the lateral dose and the implantationsconditions may depend on the original doping values or doping ratios ofthe doping regions.

The lateral homogenization of the voltage yield (and/or other electricalparameter values), may allow more freedom in the manufacturing processof the components, such as, the use of a trench concept, or a reductionin the accuracy for the doping in the epitaxial layers, for example.

FIG. 2 shows a schematic illustration of a semiconductor wafer 200according to an embodiment. The semiconductor wafer 200 comprises aplurality of compensation devices 201. Each compensation device 201comprises a plurality of device drift regions 202 having a firstconductivity type and a plurality of compensation regions 203 having asecond conductivity type arranged alternatingly in a lateral direction,x.

A breakdown voltage of more than 70% of the plurality of compensationdevices 201 varies by less than 10% from a nominal breakdown voltage ofthe plurality compensation devices 201.

Due to a breakdown voltage of more than 70% of the plurality ofcompensation devices 201 varying by less than 10% from a nominalbreakdown voltage, a plurality of semiconductor devices within asemiconductor wafer may have reduced deviations or reducedinhomogeneity.

The breakdown voltage of more than 70% (or e.g. more than 80% or e.g.more than 90%) of the compensation devices of the plurality ofcompensation devices are individually adjusted to vary by less than 10%(or e.g. by less than 5%, or e.g. less than 2%, or e.g. less than 1%)from the nominal breakdown voltage.

Compensation devices may be based on mutual compensation of at least apart of the charge of n- and p-doped areas in the drift region of thevertical electrical element arrangement. For example, in a verticaltransistor, p- and n-pillars or plates (plurality of strip shaped driftregions and plurality of strip-shaped cell compensation regions) may bearranged in pairs. For example, a strip-shaped cell compensation region203 of the plurality of strip-shaped cell compensation regions 203comprises a laterally summed number of dopants per unit area of thefirst conductivity type (p or n) deviating from half of a laterallysummed number of dopants per unit area of the second conductivity type(n or p) comprised by two strip-shaped drift regions located adjacent toopposite sides of the strip-shaped cell compensation region by less than+/−25% (or less than 15%, less than +/−10%, less than +/−5%, less than2% or less than 1%) of the laterally summed number of dopants per unitarea of the first conductivity type comprised by the strip-shaped cellcompensation region 203. The lateral summed number of dopants per unitarea may be substantially constant or may vary for different depths. Thelateral summed number of dopants per unit area may be equal orproportional to a number of free charge carriers within a strip-shapedcell compensation region 203 or a strip-shaped drift region 202 to becompensated in a particular depth, for example.

The plurality compensation regions 203 and the plurality of driftregions 202 may be stripe shaped. For example, the pluralitycompensation regions 203 and the plurality of drift regions 202 may havea vertical extension (e.g. vertical depth). In other words, thestripe-shaped cell compensation regions 203 may be laminar structures ormay comprise the geometry of a wall or plate. The vertical extension maybe larger than the lateral width and shorter than the lateral length.For example, the plurality of stripe-shaped cell compensation regions203 may extend from the first lateral side surface of the semiconductorwafer into a depth of more than 10 μm (or more than 20 μm or more than50 μm).

The stripe-shaped cell compensation regions 203 of the plurality ofstripe-shaped cell compensation regions 203 may be arrangedsubstantially in parallel to each other (e.g. neglecting manufacturingtolerances).

In a cross-section orthogonal to the lateral length of the stripe-shapedcell compensation structures 203, the stripe-shaped cell compensationregions 203 may comprise a pillar shape. The plurality of stripe-shapedcell compensation regions 203 may be arranged alternating to a pluralityof stripe-shaped drift regions 202 of the vertical electrical elementarrangement. In other words, a stripe-shaped drift region 202 of thevertical electrical element arrangement may extend into thesemiconductor wafer between each two stripe-shaped cell compensationregions 203 within a cell region of a semiconductor device compensationdevice 201. The plurality of stripe-shaped drift regions 202 maycomprise a second conductivity type.

Each compensation device may be a charge compensation transistor device.For example, each compensation device may be a MOSFET device or an IGBTdevice. For example, each compensation device may include a verticalsuper-junction (SJ) n-channel field-effect transistor (NFET), a verticalSJ p-channel FET, or a lateral SJ FET including source and draincontacts at a common side, or a lateral or vertical insulated gatebipolar transistors (IGBTs), for example.

Each compensation device may be a power semiconductor (transistor)device having a breakdown voltage or blocking voltage of more than morethan 10V (e.g. a breakdown voltage of 10 V, 20 V or 50V), more than 100V (e.g. a breakdown voltage of 200 V, 300 V, 400V or 500V) or more than500 V (e.g. a breakdown voltage of 600 V, 700 V, 800V or 1000V) or morethan 1000 V (e.g. a breakdown voltage of 1200 V, 1500 V, 1700V or2000V).

The plurality of compensation devices in the semiconductor wafer mayrefer more than one (or e.g. more than ten, or e.g. more than fifty, ore.g. more than hundreds of) compensation devices located in thesemiconductor wafer.

More details and aspects are mentioned in connection with theembodiments described above or below. The embodiments shown in FIG. 2may comprise one or more optional additional features corresponding toone or more aspects mentioned in connection with the proposed concept orone or more embodiments described above (e.g. FIGS. 1A to 1B) or below(e.g. FIGS. 3A to 3B).

FIG. 3A shows a schematic illustration of an implantation apparatus 300for implanting protons. The apparatus 300 comprises a protonimplantation module 311 configured to implant protons into asemiconductor substrate. The apparatus 300 further comprises a controlmodule 312 configured to control the proton implantation module 311 tovary an implantation dose of protons laterally, so that protons areimplanted with different implantation doses at different lateralportions of the semiconductor substrate.

Due to the control module 312 being configured to control theimplantations module to vary an implantation dose of protons laterally,a plurality of semiconductor devices within a semiconductor wafer may beprovided with reduced deviations or inhomogeneity.

The proton implantation module 311 may be configured to implant protonsinto the semiconductor substrate at an implantation dose in the range of1*10¹¹ ions per cm² and 5*10¹⁶ ions per cm² (or e.g. between 1*10¹³ ionsper cm² and 8*10¹⁴ ions per cm², or e.g. between 5*10¹³ ions per cm² and2*10¹⁴ ions per cm², or e.g. between 2*10¹⁴ ions per cm² and 8*10¹⁴ ionsper cm²). The proton implantation module may be configured to implantthe protons into the semiconductor substrate at implantation energies ofgreater than 30 keV (or e.g. greater than 300 keV, or e.g. between 30keV and 5.0 MeV, or e.g. between 1.0 MeV and 3.0 MeV), for example.

FIG. 3B shows a schematic illustration of the implantation apparatus 300for implanting protons into a semiconductor wafer (or substrate) 200.The implantation apparatus 300 may include a robot 313 and a motor 316configured to control a position of the semiconductor wafer 200. Forexample, the robot 313 and the motor 316 may be configured to control adirection of travel 314 of the semiconductor wafer 200, in a directionsubstantially parallel to a lateral surface of the semiconductor wafer,and/or such that the position of the semiconductor wafer 200 may bevaried with respect to the main beam direction of the ion beam 315 ofdoping ions. For example, the robot 313 and the motor 316 may beconfigured to control the position of the semiconductor wafer 200 suchthat the ion beam 315 may enter the semiconductor wafer 200 at differentlateral positions on the lateral side surface of the semiconductor wafer200.

The control module 312 may be configured to control the protonimplantation module 311 to vary an implantation dose of protonslaterally based on the measured electrical parameter values of theelectrical device structure in each semiconductor device in thesemiconductor wafer. The control module 312 may be configured to controlthe proton implantation module 311 to vary the implantation doses (ore.g. proton irradiation doses) and/or annealing parameters for eachsemiconductor device, for example. For example, the control module 312may be configured to control the proton implantation module 311 to varyat least one of a dose and an energy of proton irradiation based on themeasured electrical parameter values of the plurality semiconductordevices in the semiconductor substrate.

The implantation apparatus 300 may be used as part of a feed forwardmethod or concept to homogenize the doping levels (or doping ratiosbetween p-doping regions and n-doping regions) in compensationscomponents, and/or to increase the voltage yield over a chip and/or tosimplify the process for forming semiconductor devices.

The adaptation of the lateral distribution of the implantations dose maytake place by sweeping the wafer with ion beams during implantation.Through variation of the scanning speed of the wafer through the beamsand/or the speed of the sweeps of the beams over the wafer, a patternwith different doses may be implanted. Additionally or optionally, thewafer may be rotated on the plate such that the ion beam 315 (withdifferent lateral doses) may enter the semiconductor wafer 200 atdifferent lateral positions on the lateral side surface of thesemiconductor wafer 200, for example. Additionally or optionally, thewafer may be vertically (or horizontally) moved, and the ion beam may bescanned horizontally (or vertically) such that the ion beam 315 (withdifferent lateral doses) may enter the semiconductor wafer 200 atdifferent lateral positions on the lateral side surface of thesemiconductor wafer 200. Through the variation of the x-y movement ofthe semiconductor wafer, higher or lower doses may be implanted locallyor in different lateral locations of the semiconductor wafer. Forexample, inhomogeneous implantation (or unsymmetrical dose patterns) maybe carried out in target areas of the wafer. For example, defined areasmay have higher or lower doses as others. For example, off-centerpatterns and/or non-circular patterns may be implemented and complexpattern with laterally varying implantation doses may be generated tocontrol an a lateral doping profiles and the lateral distribution ofdoping ratios.

Although the movement of the semiconductor wafer with respect to ionbeam is described, it may be understood that additionally or optionally,a position of the ion beam with respect to the semiconductor wafer suchthat the ions may be implanted at different lateral positions of thesemiconductor wafer 200.

More details and aspects are mentioned in connection with theembodiments described above or below. The embodiments shown in FIGS. 3Aand 3B may comprise one or more optional additional featurescorresponding to one or more aspects mentioned in connection with theproposed concept or one or more embodiments described above (e.g. FIGS.1A to 2) or below.

Various examples relate to a method for increasing the doping efficiencyof a proton implantation and/or for partially influencing a protondoping profile, for example.

Aspects and features (e.g. the semiconductor wafer, the at least oneelectrical parameter, the semiconductor device, the electrical devicestructure, the doping ions, the laterally varying implantation doses,the device doping regions, the implantation apparatus, the protonimplantation module, the control module and the compensation devices)mentioned in connection with one or more specific examples may becombined with one or more of the other examples.

Example embodiments may further provide a computer program having aprogram code for performing one of the above methods, when the computerprogram is executed on a computer or processor. A person of skill in theart would readily recognize that acts of various above-described methodsmay be performed by programmed computers. Herein, some exampleembodiments are also intended to cover program storage devices, e.g.,digital data storage media, which are machine or computer readable andencode machine-executable or computer-executable programs ofinstructions, wherein the instructions perform some or all of the actsof the above-described methods. The program storage devices may be,e.g., digital memories, magnetic storage media such as magnetic disksand magnetic tapes, hard drives, or optically readable digital datastorage media. Further example embodiments are also intended to covercomputers programmed to perform the acts of the above-described methodsor (field) programmable logic arrays ((F)PLAs) or (field) programmablegate arrays ((F)PGAs), programmed to perform the acts of theabove-described methods.

The description and drawings merely illustrate the principles of thedisclosure. It will thus be appreciated that those skilled in the artwill be able to devise various arrangements that, although notexplicitly described or shown herein, embody the principles of thedisclosure and are included within its spirit and scope. Furthermore,all examples recited herein are principally intended expressly to beonly for pedagogical purposes to aid the reader in understanding theprinciples of the disclosure and the concepts contributed by theinventor(s) to furthering the art, and are to be construed as beingwithout limitation to such specifically recited examples and conditions.Moreover, all statements herein reciting principles, aspects, andembodiments of the disclosure, as well as specific examples thereof, areintended to encompass equivalents thereof.

Functional blocks denoted as “means for . . . ” (performing a certainfunction) shall be understood as functional blocks comprising circuitrythat is configured to perform a certain function, respectively. Hence, a“means for s.th.” may as well be understood as a “means configured to orsuited for s.th.”. A means configured to perform a certain functiondoes, hence, not imply that such means necessarily is performing thefunction (at a given time instant).

Functions of various elements shown in the figures, including anyfunctional blocks labeled as “means”, “means for providing a sensorsignal”, “means for generating a transmit signal.”, etc., may beprovided through the use of dedicated hardware, such as “a signalprovider”, “a signal processing unit”, “a processor”, “a controller”,etc. as well as hardware capable of executing software in associationwith appropriate software. Moreover, any entity described herein as“means”, may correspond to or be implemented as “one or more modules”,“one or more devices”, “one or more units”, etc. When provided by aprocessor, the functions may be provided by a single dedicatedprocessor, by a single shared processor, or by a plurality of individualprocessors, some of which may be shared. Moreover, explicit use of theterm “processor” or “controller” should not be construed to referexclusively to hardware capable of executing software, and mayimplicitly include, without limitation, digital signal processor (DSP)hardware, network processor, application specific integrated circuit(ASIC), field programmable gate array (FPGA), read only memory (ROM) forstoring software, random access memory (RAM), and non-volatile storage.Other hardware, conventional and/or custom, may also be included.

It should be appreciated by those skilled in the art that any blockdiagrams herein represent conceptual views of illustrative circuitryembodying the principles of the disclosure. Similarly, it will beappreciated that any flow charts, flow diagrams, state transitiondiagrams, pseudo code, and the like represent various processes whichmay be substantially represented in computer readable medium and soexecuted by a computer or processor, whether or not such computer orprocessor is explicitly shown.

Furthermore, the following claims are hereby incorporated into theDetailed Description, where each claim may stand on its own as aseparate embodiment. While each claim may stand on its own as a separateembodiment, it is to be noted that—although a dependent claim may referin the claims to a specific combination with one or more otherclaims—other embodiments may also include a combination of the dependentclaim with the subject matter of each other dependent or independentclaim. Such combinations are proposed herein unless it is stated that aspecific combination is not intended. Furthermore, it is intended toinclude also features of a claim to any other independent claim even ifthis claim is not directly made dependent to the independent claim.

It is further to be noted that methods disclosed in the specification orin the claims may be implemented by a device having means for performingeach of the respective acts of these methods.

Further, it is to be understood that the disclosure of multiple acts orfunctions disclosed in the specification or claims may not be construedas to be within the specific order. Therefore, the disclosure ofmultiple acts or functions will not limit these to a particular orderunless such acts or functions are not interchangeable for technicalreasons. Furthermore, in some embodiments a single act may include ormay be broken into multiple sub acts. Such sub acts may be included andpart of the disclosure of this single act unless explicitly excluded.

With the above range of variations and applications in mind, it shouldbe understood that the present invention is not limited by the foregoingdescription, nor is it limited by the accompanying drawings. Instead,the present invention is limited only by the following claims and theirlegal equivalents.

What is claimed is:
 1. A method for forming a semiconductor device, themethod comprising: determining at least one electrical parameter foreach semiconductor device of a plurality of semiconductor devices to beformed in a semiconductor wafer; and implanting doping ions into deviceareas of the semiconductor wafer used for forming the plurality ofsemiconductor devices with laterally varying implantation doses based onthe at least one electrical parameter of the plurality of semiconductordevices, wherein the at least one electrical parameter is an electricalbreakdown voltage of at least one semiconductor device of the pluralityof semiconductor devices.
 2. The method of claim 1, wherein the dopingions are implanted into a device area of a first semiconductor device ofthe plurality of semiconductor devices with a first implantation dose,and into a device area of a second semiconductor device of the pluralityof semiconductor devices with a second different implantation dose,wherein the first semiconductor device and the second semiconductordevice are located at different lateral portions of the semiconductorwafer.
 3. The method of claim 1, wherein the doping ions are implantedinto a device area of at least one semiconductor device of the pluralityof semiconductor devices to adjust the at least one electrical parameterrelated to the semiconductor device to vary by less than 10% from apredefined nominal electrical parameter value.
 4. The method of claim 1,wherein the doping ions are implanted into the device areas of thesemiconductor devices of the plurality of semiconductor devices suchthat the at least one electrical parameter of more than 70% of thesemiconductor devices of the plurality of semiconductor devices areindividually adjusted to vary by less than 10% from a predefined nominalelectrical parameter value.
 5. The method of claim 1, wherein the dopingions are implanted into the device areas of the semiconductor deviceswith laterally varying implantation doses of between 1*10¹³ ions per cm²and 8*10¹⁴ ions per cm².
 6. The method of claim 1, wherein the dopingions are protons.
 7. The method of claim 1, wherein the doping ions areimplanted into the device areas of the semiconductor devices withlaterally varying implantation doses by varying a speed of motion, anangle, or a distance of the semiconductor wafer with respect to an ionbeam implanting the doping ions.
 8. The method of claim 1, furthercomprising forming device doping regions of an electrical devicestructure in each device area of the plurality of semiconductor devicesbefore implanting the doping ions into the device areas of the pluralityof semiconductor devices with laterally varying implantation doses. 9.The method of claim 8, wherein the device doping regions are formed inthe semiconductor wafer within a trench and/or by ion implantationbefore implanting the doping ions.
 10. The method of claim 8, whereinthe device doping regions comprise a plurality of drift regions having afirst conductivity type and a plurality of compensation regions having asecond conductivity type arranged alternatingly in a lateral direction.11. The method of claim 1, further comprising forming a source/drain oremitter/collector contact structure on at least one side of thesemiconductor wafer after implanting the doping ions into the deviceareas of the plurality of semiconductor devices.
 12. The method of claim1, further comprising annealing the semiconductor wafer after implantingdoping ions into the device areas of the plurality of semiconductordevices with laterally varying implantation doses.
 13. The method ofclaim 12, wherein the semiconductor wafer is annealed at a temperatureof between 380° C. and 500° C.
 14. The method of claim 12, wherein thesemiconductor wafer is annealed for between 0.5 hours and 10 hours. 15.The method of claim 1, wherein each semiconductor device to be formedcomprises at least one electrical device structure from the followinggroup of electrical device structures, the group of electrical devicestructures consisting of: a metal oxide semiconductor field effecttransistor device structure; an insulated gate bipolar transistor devicestructure; a charge compensation transistor device structure; a diodestructure; and a thyristor structure.
 16. The method of claim 1, whereineach semiconductor device to be formed has a blocking voltage of greaterthan 10 V.
 17. An implantation apparatus for implanting protons, theapparatus comprising: a proton implantation module configured to implantprotons into a semiconductor substrate; and a control module configuredto control the proton implantation module so as to vary an implantationdose of protons laterally based on a measured electrical parameter valueof a semiconductor device in the semiconductor substrate, such that theprotons are implanted with different implantation doses at differentlateral portions of the semiconductor substrate, wherein the measuredelectrical parameter value is an electrical breakdown voltage of thesemiconductor device.
 18. The implantation apparatus of claim 17,wherein the proton implantation module is configured to implant theprotons into the semiconductor substrate at implantation energies ofgreater than 300 keV.
 19. A semiconductor wafer, comprising: a pluralityof compensation devices, wherein each compensation device comprises aplurality of device drift regions having a first conductivity type and aplurality of compensation regions having a second conductivity typearranged alternatingly in a lateral direction, wherein a breakdownvoltage of more than 70% of the plurality of compensation devices variesby less than 10% from a nominal breakdown voltage of the pluralitycompensation devices.